Polyolefins are widely used to produce containers for food products. In particular, polypropylene heterophasic compositions, due to their impact resistance properties that extend at low temperatures, are known to be indicated for use in the production of containers for food products that can be frozen.
For Example US 2001/0017301 relates to a inner container that can be made by using a generic heterophasic copolymer.
Heterophasic polypropylene compositions are also known for other purposes. For example, WO 2006/037705 relates to an olefin polymer composition comprising (by weight, unless otherwise specified):    A) 60-85%, preferably 65-80%, more preferably 65-75%, of a crystalline propylene homopolymer or a crystalline copolymer of propylene containing 3% or less of ethylene or C4-C10 alpha-olefin(s) or of combinations thereof, said homopolymer or copolymer having a Polydispersity Index (P.I.) value of from 4.5-6, preferably 4.5-5.5, and a content of isotactic pentads (mmmm), measured by 13C NMR on the fraction insoluble in xylene at 25° C., higher than 96%, preferably higher than 98%;    B) 15-40%, preferably 20-35%, more preferably 25-35%, of a partially amorphous copolymer of ethylene containing from 35% to 70%, preferably from 40 to 55%, of propylene or C4-C10 alpha-olefin(s) or of combinations thereof, and optionally minor proportions of a diene. Said olefin polymer composition exhibits a value of elongation at break ranging from 150 to 600%, preferably 200-500%, according to ISO method 527.
The composition described in this document is said to be fit for automotive applications in particular for bumpers.
WO 05/014713 relates to a heterophasic polyolefin composition comprising (percent by weight):    1) 65-95% of a crystalline propylene polymer selected from propylene homopolymer and random polymer of propylene with 0.1-10% of an a-olefin selected from ethylene, a C4-C10 alpha-olefin and a mixture thereof, the said polymer being insoluble in xylene at ambient temperature in an amount over 85% and having a polydispersity index ranging from 4 to 13, preferably 4.5 to 12, more preferably 5 to 9, and an intrinsic viscosity value over 2.2 dl/g, preferably 2.2 to 4.5 dl/g; and    2) 5-35% of an elastomeric olefin polymer of ethylene with a C3-C10 alpha-olefin and optionally a diene, having an ethylene content ranging from 15 to 85% and an intrinsic viscosity value of at least 1.4 dl/g, preferably from 2.5 to 5 dl/g.
The composition described in this document is particularly fit for the production of pipes.
WO 2004/087807 relates to a propylene polymer composition comprising (by weight, unless otherwise specified):    A) 60-95%, of a propylene homopolymer, or a copolymer of propylene containing 3% or less of ethylene or C4-C10 alpha-olefin(s) or of combinations thereof, said homopolymer or copolymer having a Polydispersity Index (P.I.) value of from 4.6 to 10, preferably from 5.1 to 8 and a content of isotactic pentads (mmmm), measured by 13C NMR on the fraction insoluble in xylene at 25° C., higher than 98 molar %, preferably from 98.5 to 99.5 molar %;    B) 5-40%, preferably 10-35%, of a copolymer of ethylene containing from 40% to 70%, preferably from 47 to 62%, of propylene or C4-C10 alpha-olefin(s) or of combinations thereof, and optionally minor proportions of a diene; said composition having a Temperature Rising Elution Fractionation (TREF) profile, obtained by fractionation in xylene and collection of fractions at temperatures of 40° C., 80° C. and 90° C., in which the ethylene content Y of the fraction collected at 90° C. satisfies the following relation (I):Y←0.8+0.035X+0.0091X2 wherein X is the ethylene content of the fraction collected at 40° C. and both X and Y are expressed in percent by weight (referred to the respective fractions), and having a value of intrinsic viscosity of the fraction soluble in xylene at 25° C. of from 1.8 to 4.2 dl/g, preferably from 2 to 4.2 dl/g, more preferably from 2.3 to 3.8. This composition has preferably a Melt Flow Rate (MFR) from 0.5 to 45 g/10 min., more preferably from 2 to 35 g/10 min. This document does not report possible use for the composition.